Flatten a given array of arbitrarily nested arrays of integers into a flat array of integers. e.g. [[1,2,[3]],4] -> [1,2,3,4].

flatten.php

<?php
function flatten_array ( $temp = array(), $flatten=array() ) {
  foreach ($temp as $key => $value) {
    if (is_array($value)) {
      $flatten = flatten_array ($value, $flatten);
    } else {
      $flatten[] = $value;
    }
  }
  return $flatten;
}

#Example:

# Given
# [[1,2,[3]],4] are same structure below
$temp = array(
  array(
    '1',
    '2',
    array('3')
  ),
  '4'
);

$flatten = flatten_array ($temp);
var_dump($flatten);
?>